Curing and rheological behavior of vinyl ester resins prepared in the presence of tertiary amines

摘要

Vinyl ester resins V_1, V_2 & V_3 of acid value (approx6 mg KOH g~(-1) solid) were synthesized using bisphenol-A epoxy and acrylic acid in the presence of triethyl-, tripropyl- and tributyl-, amines in 210, 270 and 340 minutes, respectively. The synthesized resins were characterized by FTIR spectroscopy and a new peak at 2360 cm~(-1) was observed which is due to attachment of amines to resin structure by hydrogen bond. The curing behavior of synthesized resin containing 40% styrene (w/w) and 2% benzoyl peroxide was studied using DSC technique and found to be affected by presence of amines. Activation energy and frequency factor for the curing reaction increases from 14 Kcal mol~(-1) to 23 Kcal mol~(-1). Rheological behavior of resins containing 40% styrene was studied using a Haake Rotovisco RV20 viscometer, and viscosity was found to increase with shear rate up to 200 sec~(-1). The average values of activation energy at constant shear stress (6-15 Pa) were 12.94, 13.20, 13.70 Kcal mol~(-1) for V_1, V_2 and V_3, respectively. The activation energy at constant shear rate decreases with an increase in the shear rate.